beta-delayed-neutron studies of Sb-135,Sb-136 and I-140 performed with trapped ions

Beta-delayed-neutron (beta n) spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The beta n branching ratios and energy spectra for Sb-135,Sb-136 and I-140 were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having beta n branching ratios that impact the r-process abundance pattern around the A approximate to 130 peak. For Sb-135,Sb-136 and I-140, beta n branching ratios of 14.6(13)%, 17.6(29)%, and 7.6(28)% were determined, respectively. The beta n energy spectra obtained for Sb-135 and I-140 are compared with results from direct neutron measurements, and the beta n energy spectrum for Sb-136 has been measured for the first time.